This invention relates to a novel polymer optical waveguide possessing a high degree of flexibility. More particularly, the polymer optical waveguide of this invention contains a thermoplastic aliphatic segmented polyurethane core.
An optical waveguide comprises a core of a material which transmits light and a clad surrounding the core wherein the refractive index of the clad is lower than the refractive index of the core, such that lightwaves transmitted down the core are not refracted out at the core/clad interface but are instead reflected back into the core of the waveguide. The light transmitted through the optical waveguide can be used for illumination, data transmission, and other optical and information transmission purposes. An optical waveguide must be comprised of a material which is optically clear with low attenuation. Low attenuation means the optical waveguide loses little light as the light is transmitted down the waveguide. The optical waveguide must possess sufficient flexibility to be able to withstand handling and bending during processing and use without deleteriously affecting its physical integrity or light transmitting capabilities. An optical waveguide should also possess sufficient strength and sufficient temperature use capability.
Early optical waveguides were predominantly comprised of silica glass. However, optical waveguides comprised of glass possess a low degree of flexibility. The elongation at break is low and the bending radius at break is large. Glass optical waveguides are also low in strength with respect to impact shock and twisting. More recently, optical waveguides have been fabricated from optically clear polymers which transmit light. Polymer optical waveguides to date have been fabricated from relatively hard, glassy polymers such as acrylics or styrenics. These glassy polymers also possess a low degree of flexibility.
What is needed is a polymer optical waveguide with low attenuation and a high degree of flexibility. Sufficient strength and sufficient temperature use capability are also needed.